Transactions made between business organizations or the like have been conventionally performed by way of paper medium documents. However, transactions by way of electronic document are being performed in recent years. Further, as a result that legislation such as an electronic signature law and an e-document law has been developed, there are performed transactions by way of exchanging electronic documents in which electronic signatures are available, such as an electronic contract in which a contract is made by exchanging electronic documents. Since documents are often repeatedly exchanged between business organizations or the like, it is beneficial to introduce a mechanism to perform transactions by way of electronic documents in which electronic signatures are available, even if some trouble is involved in initial use.
In recent years, transactions by way of electronic documents in which electronic signatures are available are performed not only between business organizations but have begun to be broadly performed. For example, there can be supposed a case where, in a contract for an individual made for the sake of construction for the individual, a signature in a construction request order or the like from the individual is electronically handwritten when a contract procedure is performed at the individual's home.
However, it is sometimes questionable whether or not that handwritten electronic signature is authentic and is difficult of proof, and further, there is a problem that a handwritten electronic signature, which is image data and copying and editing is possible, is weak as a method of confirming that the person himself has signed.
In order to solve the problem of identification and falsification as above, use of an electronic certificate is known, but there is a problem that use of the electronic certificate takes a lot of trouble with preparation. In a transaction with an individual, etc., it is often the case that documents are exchanged only once, and it is quite unlikely to use an electronic certificate which takes a lot of trouble with preparation for just one transaction.
It is convenient if a light user for personal use or the like can perform a transaction requiring a signature by way of an electronic document without trouble, so that electronic documents are likely to become widespread to thereby promote paperless.